Orthodontic brace

ABSTRACT

An orthodontic brace which is easy to use and which will optimize the relation between moment and force includes a guide mechanism that includes an upper bending stable mounting bar, two lower mounting bars, and substantially rectilinear wires connected between the upper mounting bar and each of the lower mounting bars. The lower mounting bars are fastened to an arch wire or a bracket on the teeth desired to be moved by fastening locks. As the springs of the orthodontic brace are made up of the wires, which are made from a superelastic material, and which are fixed in the bars, a desired moving, in relation to another tooth segment, may be obtained in form of a translation, which possibly is combined with a rotation of a tooth segment. The desired movement depends on the form of the guide mechanism. The applied force will substantially be constant, and due to the torsion stable guide mechanism, which with torsion stability is connected with a tooth to be moved, a self-adjusting contribution of moment is obtained. Consequently, an unintended rotation is obviated during movement.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an orthodontic brace of the type thatincludes spring formed of a superelastic material for establishingmovement of the teeth desired to be moved, and fastening means which areintended for fastening the spring means to force-transmitting meanswhich are connected with the teeth for transmitting the actuation forceof the spring means to the teeth desired to be moved.

2. The Prior Art

For a correction of misaligned teeth small locks are placed on theteeth, these locks are so-called brackets, in which it is possible tomount different types of wires, depending on the type of tooth movementdesired to be carried out.

In the majority of all cases orthodontics is carried out by means ofcontinuous arches along which the tooth movements are carried out. Thistechnique, which is called the straight-wire-technique, is connectedwith drawbacks as friction arises between the locks and the wires, andas it is difficult to carry out a parallel translation along the arch.Furthermore, it is only possible to carry out tooth movements in thedirection of the arch.

In order to overcome the drawbacks of the straight-wire-technique, aso-called segmented technique has been developed in which speciallyshaped braces are applied between groups of teeth, which braces supplyforces and momenta resulting in the tooth movements. Using thistechnique the correction of the misaligned teeth may be controlled in amore precise way.

However, this requires a thorough knowledge of the relations between thegeometry of the teeth, bone support, and the mechanical properties ofthe braces. It is especially important to have a precise knowledge ofhow forces and momenta are released from these braces in order to obtaina desired tooth movement. Though the arches remedy some of the drawbacksof the straight-wire-technique, they are complicated to use as greatdegree of manual adjusting and a large professional skill is required inorder to correctly apply and use the known braces. Furthermore, theknown braces will not make it possible in all situations to obtaindesired relations between moment and force during tooth movement, whichoccurs after applying the known braces.

It is also difficult to relate the forces and momenta directly to theso-called centre of resistance for a tooth. The centre of resistance isdefined as the point through which the effect from simple force willresult in a translation. The centre of resistance will normally bepositioned approximately in the centre of a root of a tooth, that is tosay, in the jawbone approximately 1/3 from the tip of the root. As theteeth are affected via brackets which are positioned on the crowns ofteeth, a simple force acting on a bracket will result in a combinedtranslation and rotation of a tooth or a tooth segment which isaffected. On the contrary, a pure translation of a tooth is obtained byapplying a combined force and a moment on the brackets used. When therelation between the applied moment and the applied force vary,different tooth movements are obtained, which may be a pure translation,a combined translation and rotation, or a simple rotation around thecentre of resistance.

A drawback of the known techniques is the need for optimizing theactuation on the teeth in order to obtain tooth movement relative tobiomechanical properties. Thus, it it desired to keep the forceactuation within limits in which an optimizing of the biomechanicalsystem occurs, so that tooth movement takes place with a speed that isas optimal as possible. This relation should also be compared to thedesire to minimize adjustments of the actuation means, as this normallyrequires a consultation.

Another important aspect is that a tooth movement with great actuationforce will also cause much unpleasantness for the patient. Accordingly,through experience it has been found that an optimal force should bebetween approximately 50 cN and 250 cN. In order to obtain such acomparative, well-defined and constant force, it has been previouslysuggested, e.g., from U.S. Pat. No. 4,849,032, to use springs from asuperelastic material, as a substantially constant force may be obtainedover a comparatively long spring compression. That is to say,establishment of springs which do not follow Hookes' Law of linearelastic materials.

Though the use of the superelastic springs will highly comfort thepatient and simultaneously give the possibility of less frequentconsultations for checking the orthodontic brace, the use will notremedy the above-mentioned drawbacks with uncertain tooth movements.

It is the object of the present invention to remedy the above-mentioneddrawbacks and to provide an orthodontic brace which also makes itpossible to carry out orthodontic correction of misaligned teethaccording to the two known fundamentals, that is to say, with thestraight-wire-technique and the segmented technique, and whichsimultaneously will be very easy to use and wherein a precise and uniquetooth movement is obtained. At the same time, it is the object that theorthodontic brace can be prefabricated, and that there will be nosubsequent need for individual adjustment and adaption when using theorthodontic brace.

SUMMARY OF THE INVENTION

These objects are attained according to the present invention with anorthodontic brace of the above-mentioned type, characterized in that theorthodontic brace includes a guiding mechanism with a bending stable,upper mounting bar and two bending stable, lower mounting bars whichextend substantially parallel to the upper mounting bar, and which bymeans of the fastening means is fastened for forced rotation togetherwith the force-transmitting means, which may optionally be constitutedof a bracket adhered to a tooth or an arch wire connected with severalteeth via brackets, that the upper mounting bar is connected with eachof the lower mounting bars by means of at least two substantiallyrectilinear and parallel wires, and that the spring means resilientlyactuate the two lower mounting bars.

With such an orthodontic brace it will be possible to obtain asubstantially constant actuation force, which may be optimized withinthe desired force level, irrespective of whether astraight-wire-technique is used in which the guide mechanism isconnected with an arch wire, or a segmented technique in which the guidemechanism is connected with a bracket directly onto a tooth or a toothsegment. It will also be possible to use a straight-wire-technique incombination with a segmented technique on the tooth or the toothsegment, which is located adjacent an orthodontic brace, which isinserted instead of a portion of a traditional arch wire.

With an orthodontic brace according to the invention a self-adjustingcontribution of moment is formed. Because of the structure of the guidemechanism with a joint connection between the upper mounting bar andeach of the lower mounting bars, the orthodontic brace will not incur amoment on the teeth. Here it is a condition that the joint connectionbetween the bars is constituted of wires having identical lengths forobtaining a translation.

First the spring means are tightened in such a way that a joining orseparating force is obtained between the two lower mounting bars. Thiscauses an initial translation of the tooth or teeth desired to be moved,and possibly give rise to a moment because of the forced rotationconnection between a mounting bar and a force-transmitting means.Because of the forced rotation connection any tendency to mutualrotation will be conteracted by an opposite acting moment. At once whenthe tendency to mutual rotation disappears, and thus only a puretranslational displacing of the tooth or teeth appears, the establishedmoment will disappear too. Thus, the system does not give risk of movingthe teeth in form of rotation, which may cause incorrect movement of theroot or crown.

As the mounting bars are bending stable, or in any case have such abending stability to transmit forces which are formed by activating thespring means, a tooth movement will always occur according to the mutualmovement of the two lower mounting bars, which is determined by thelength of the wires. As a self-adjusting moment is also obtained, thetooth movement will always be a translational movement with the mutualorientations of the teeth, which initially are established through theforced rotation connection between the mounting bars and theforce-transmitting means, which are fastened to the tooth or the toothsegment desired to be moved.

According to the invention the orthodontic brace is very flexible as theforce/moment combination, which is established by means of the brace,may very easily be controlled merely by changing the length of one ofthe wires for the lower mounting bar or both the lower mounting bars.This may easily be established when the upper mounting bar is made frommoulded materials, preferably plastics. By forming a projecting portionon the upper and/or lower mounting bar and connecting the wire hereto,the length of the wire is changed, and hereby a joining or separatingmovement of the two mounting bars will not occur according to a straightline but through a swinging movement. Because of the forced rotationconnection with the force-transmitting means on the tooth or teeth, thisswinging movement will give rise to a force/moment combination. Therelation between the moment and the force may rather easily be adjusted,and due to the use of a superelastic spring, it will be a constantrelation, irrespective the degree of contraction or separation of teeth,which is established with the orthodontic brace. Thus, by segmentedmoving of a single tooth, a movement may be established in which boththe moment and the force will be constant during the movement.Consequently, the tooth desired to be moved may be provided with acombined translation and rotation. Hereby, it will be possible to carryout a simultaneous translation and rotation of a tooth or a toothsegment.

The use of the orthodontic brace for actual orthodontic correction ofmisaligned teeth will be simple. The mounting of the orthodontic bracewill also be simple with fastening means which will actually be put onlike a clip by guiding the U-shape around the rod-shaped portion of thelower mounting bars and an arch wire or a rod-shaped portion, which areintended for engaging a single bracket by a segmented tooth movement.

The fastening means ensure that the orthodontic brace is torsion stable.It will be easy to adjust after being mounted. The pawl is merelydisplaced by turning the nut. Consequently, the rods or the wires, whichare accommodated in the interior of the U, are fastened. Before completetightening of the two nuts a tensioning of the spring means is carriedout. After the nut is tightened the spring means will be secured in thetensioned state. This tensioning may easily and uncritically be carriedout as a very precise adjustment of the orthodontic brace is notrequired. Because of the superelastic springs, the orthodontic bracewill establish the desired spring force, even with a rather coarsetensioning.

Except for the above-mentioned advantages, an orthodontic braceaccording to the invention will be advantageous by having a very smallthickness. Thus, it will not be uncomfortable for a user as the mountingbars may be moulded in a thin plastic material, which will not feeluncomfortable against the gums of the user. Moreover, this means thatthe orthodontic brace will be very sanitary in use. Furthermore, theorthodontic brace will be comfortable for the user because of asubstantially constant force at a level, which does not causeunpleasantness due to high levels of force.

DESCRIPTION OF THE DRAWINGS

The invention will now be explained in further detail with reference tothe accompanying drawings wherein

FIG. 1 shows a side view of an embodiment of an orthodontic braceaccording to the invention,

FIGS. 2-4 show views of fastening means, which forms part of theorthodontic brace shown in FIG. 1,

FIG. 5 shows a side view of another embodiment of an orthodontic braceaccording to the invention,

FIGS. 6 and 7 show views for illustrating fastening means, which is usedin the orthodontic brace shown in FIG. 5,

FIGS. 8-15 show views of further embodiments of orthodontic bracesaccording to the invention,

FIGS. 16-18 show views of teeth for explaining the segmented orthodontictechnique,

FIG. 19 shows a curve for illustrating the relation between rotation andmoment of a wire-pair for supporting a lower mounting bar,

FIGS. 20-23 show views for illustrating the use of the orthodontic braceof FIG. 1 on the tooth segments shown in FIG. 16,

FIGS. 24 and 25 show views for illustrating the use of the orthodonticbrace of FIGS. 12 and 13, and

FIGS. 26 and 27 show views corresponding to FIGS. 24 and 25 forillustrating the use of the orthodontic brace of FIGS. 14 and 15.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows an orthodontic brace 1 according to the present invention.The orthodontic brace comprises a guiding mechanism 2 with a bendingstable upper mounting bar 3 and two bending stable lower mounting bars4. The lower mounting bars 4 extend substantially parallel to the uppermounting bar. However, one or both of the lower mounting bars may bepositioned at an angle compared to the upper mounting bar, as it will beexplained later.

The upper mounting bar 3 is connected with each of the lower mountingbars by means of two substantially perpendicular and parallel wires 5.Each of the lower mounting bars 4 is connected with a rod 6. The rod 6is intended for connection with an arch wire 7 (see FIG. 16) or directlywith a bracket B (see FIG. 16) by means of fastening means 9, which willbe further explained with reference to FIGS. 2-4.

The orthodontic brace comprises spring means of a superelastic material.In this embodiment the spring means are made up of the actual wires 5,which each is restrained in the mounting bars 3,4. The upper mountingbar is preferably made from a biologically compatible plastic materialinto which the wires 5 are moulded in order to establish the restraint.The lower mounting bars 4 may also be made from a plastic material intowhich the wire is moulded. Alternatively, the lower mounting bars 4 maybe made from hollow tubes, which are brazed to the rods 6. Hereby, theends of the wires 5 are fastened in the hollow tubes by a clamping ofthis, such that the superelastic material may be fastened without use ofwelding or brazing.

Each of the pair of wires 5 which connect to a lower mounting bar 4 ispreferably formed by a single piece of wire having a circular sectionwhich is bent to a rectangular shape, the free ends of which areinserted into each end of the tube 30 (see FIG. 7), which constitutes aportion of the lower mounting bar 4. Thus, a side length of bent wirewill be moulded into the upper mounting bar 3, while another side lengthwill be clamped in a lower mounting bar 4. Hereby, a safe fastening isobtained so that each of the wires 5 acts as a restrained beam in themounting bars 3,4.

FIGS. 2-4 show fastening means 9 seen from different views. Thefastening means 9 is made up of a U-shaped strip of sheet metal 10. Atboth corners in each end a rectangular portion of the sheet metal stripis removed so that a central portion remains, of which the outermostportion is bent to form a flap 11. In the shown embodiment the flap,which may pass through the interior of a nut 12, will be accommodated ina recess 13 which is formed in the side of the nut, which faces awayfrom the lower portion 14 of the U. Hereby, the nut appears with anouter smooth side 15 as it is shown in FIGS. 3 and 4. Thus, the nut isheld in place between the flap 11 and the top side 16 of thestrip-shaped portion, which remains after the removal of a rectangularcorner portion. Between the central flap-shaped portions 11 adisplaceable pawl 17 is positioned, which is provided with a screwthread 18 that engages the screw thread 19 of the nut. Thereby, duringthe rotation of the nut 12 it will be possible to displace the pawl 17in the space between the two branches 20,21 of the U. Hereby, a rod 6and an arch wire 7 may be clamped in the interior of the U.

As the bottom 14 of the U is formed by two substantially plane surfaces22,23, which form a V-shape, the wires 7 with varying diameters will besafely clamped. By providing the interior end of the pawl 17 havingangled surfaces 24,25 the same effect is obtained. If the rods 6 have arectangular cross section, the angled surfaces 24,25 of the pawl willhave a very short extension, as illustrated in FIG. 3. If the rod 6 hasa round cross section, the bottom side of the pawl will substantiallycorrespond to the bottom of the U. The mutual angle 26 between the planesurfaces 22,23 may be between 30' and 120'. In order to obtain atorsion-stable fastening of wires 7 and rods 6, the strip has a widththat is 2-10 times the distance between the branches 20,21 of the U.

FIG. 5 shows another embodiment of an orthodontic brace 1A according tothe invention. The orthodontic brace 1A substantially corresponds to theone shown in FIG. 1. In FIG. 5 the upper mounting bar 3 is made with agreater length so that each of the pair of wires 5,5 is positionedside-by-side and not overlaying each other. In this embodiment the lowermounting bars 4 are directly connected with fastening means 27.

As it clearly appears from FIGS. 6 and 7, the fastening means basicallyfunction as the above-mentioned fastening means 9. The fastening means27 comprise a so-called Allen screw 28. The screw 28 is mounted on aconsole 29 to which a tube 30 is also mounted. The tube 30 is used foraccommodating the superelastic wire 5, which remains secured in this bypinching the tube 30. The arch wire or a wire length which is fasteneddirectly onto the brackets on the teeth is clamped by an eccentricrotatable pawl 31 that is provided with a flange 31', which clamps thearch wire (not shown) in a spacing between the rotatable pawl 31 and abranch 32 which is connected with the console 29.

FIGS. 8-11 illustrate further embodiments of orthodontic bracesaccording to the invention. It is noted that all embodiments areillustrated with fastening means of the integral type, which areillustrated in FIG. 5. However, it will also be possible to make theseembodiments with separate fastening means, as illustrated in FIG. 1.

In FIG. 8 the upper mounting bar 3 is made with a length correspondingto the length shown in FIG. 5. The upper mounting bar consists of twomutual telescopic portions 33 and 34. The bar portion 33 has a smallerdimension so that the telescopic portion may be inserted in an outer barportion 34. The mutual position of the two bar portions 33,34 is ensuredby means of locking means 35, which may be a screw, a friction coupling,or similar releasable elements, which in active position may prevent amutual displacing of the bar portions 33,34. Thus, this embodiment willbe suitable for carrying out tooth movement over rather large distances,as the upper mounting bar is adjusted to a new length after an initialtooth movement.

FIG. 9 illustrates another embodiment which substantially corresponds tothe embodiment shown in FIG. 8. In FIG. 9 the upper mounting bar 3consists of two end portions 36,37, which are mutually displaceable on acentral rod 38. The mutual displacing of the bar portions 36,37 isestablished by means of a screw 39.

It is a common feature for the above-mentioned embodiments which areillustrated in FIGS. 1,5,8, and 9 that the the superelastic spring meansare made up of restrained wires 5. In the two embodiments illustrated inFIGS. 10 and 11, the wires 5 are hinged to the upper 3 and lower 4mounting bars via hinge connections 40. Thus, no springing may beobtained in the wires 5, which may be made from any suitable material.In FIG. 10 the spring force is established by means of a coil spring 41of a superelastic material. The coil spring 41 is positioned between thetwo mounting bars 4, and may be both a tension and pressure spring. InFIG. 11 the spring is formed by a U-shaped spring 42, which is connectedwith the two mounting bars 4. The spring 42 may also be a tension orpressure spring.

As it appears from the above, all embodiments are able to carry out acorrection of misaligned teeth both by joining and separating the teethor tooth segments, which increases the flexibility of the orthodonticbrace 1. Thus, an orthodontic brace according to the invention and toany embodiment illustrated in FIGS. 1-9 is completely symmetrical, andwith equal effect will be able to be used for joining or separatingteeth and/or tooth segments. FIGS. 12-15 illustrate embodiments of anorthodontic brace which is not symmetrical, and which makes morecomplicated orthodontic corrections possible.

FIGS. 12-15 illustrate two examples of orthodontic braces in which theguiding mechanisms 2 are asymmetrical by using wires 5 with differentlengths. It is noted that the embodiment, which is illustrated in FIGS.12 and 13, is made from elements which are identical with the elementsin the embodiment which is shown in FIGS. 14 and 15.

FIGS. 12 and 13 illustrate a situation in which a wire 5' is shorterthan the other wires 5, which is used to connect the upper mounting bars3 with the lower mounting bars 4. The shorter wire 5' is connected witha projecting portion 43 of the upper mounting bar 3. In FIGS. 12 and 13it is assumed that the left mounting bar 4 is fastened to the teethwhich are secured, and which appear as an anchor, while the rightmounting bar is connected with the tooth or the tooth segment to bemoved (see succeeding FIGS. 24 and 25). FIG. 12 illustrates theorthodontic brace during the mounting on the teeth, and FIG. 13illustrates the orthodontic brace after the tooth movement has takenplace. In the embodiment shown in FIGS. 12 and 13, the lower mountingbar 4 illustrated in the right side is pivoted at the same time it istranslated. This results in the connected bracket and the tooth beingpivoted and translated.

In FIGS. 14 and 15 it is also the lower mounting bar 4 at the left side,which is intended to be positioned onto the secured teeth, while themounting bar 4 at the right side is connected with the tooth or thetooth segment desired to be moved. In this situation a combinedtranslation and rotation is also obtained, but the rotation will occurwith opposite orientation of the rotation established in FIGS. 12 and13.

In FIGS. 12-15 the orthodontic brace is shown with separate fasteningmeans 9 of the type which are illustrated in FIGS. 2-4. However, it isalso possible to provide these embodiments with fastening means 27 ofthe type which are illustrated in FIGS. 6 and 7.

In FIGS. 12-15 only one of the wires 5' has a shorter length than theothers. However, it will also be possible that one of the wires 5 whichare connected with the left mounting bar is made shorter and connectedto the projecting portion 43 of the upper mounting bar 3.

Now that different embodiments of an orthodontic brace according to theinvention have been explained, an explanation of how these orthodonticbraces are used during the correction of irregular teeth willsubsequently be given.

The use of the orthodontic brace according to the invention will beexplained in connection with segmented orthodontic correction, as anunderstanding of the use in connection with the thestraight-wire-technique will appear for a skilled in the art in thelight of this explanation, which is given on the orthodontic brace andits use in connection with segmented orthodontic correction techniques.

FIG. 16 shows two tooth segments 44,45. The teeth in each tooth segment44,45 are connected by means of an arch wire 7 and brackets 8. Anorthodontic brace according to the invention is intended to be mountedon top of the arch wire 7 at a position 46 between the two teeth, aswill be explained later.

The roots of the teeth 47 are positioned in the jaw bone, while thecrowns 48 of the teeth are free. The brackets 8 used are adhered on thecrowns 48 of the teeth. An actuation force of the teeth may only occurthrough the adhered brackets. The adhered brackets are arranged at adistance from the so-called centre of resistance 49 (see FIG. 17), whichis in or at the root 47 of a tooth. The centre of resistance 49 is awell-defined feature within the orthodontic correction technique and isdefined as the geometrical point where a force 50 on a segment is to beapplied in order to provide a translational movement 51 for a tooth or atooth segment in the direction of the force.

FIG. 17 shows the centre of resistance 49 of the segment 44. Theposition of the tooth segment 44 before the actuation force is shownwith dark lines, while the position of the tooth segment 44 after atranslational displacement is shown with light lines.

As a bracket 8 usually is positioned at a distance 52 from the centre ofresistance 49, a moment 53 will be required as illustrated in FIG. 18,which together with the force 50 on a bracket, make it possible toobtain a translation of a tooth segment or a tooth. As mentionedpreviously, the relation between moment and force is of great importancein orthodontic correction of misaligned teeth. It is also commonly knownthat in order to obtain correct tooth movement, it is essential thatduring the tooth movement a force is added as constant as possible. Thissubstantially constant force is obtained by using springs of asuperelastic material.

FIG. 19 shows a curve 54 for illustrating the relation between thebending moment measured in Ncm as abscissa and an angular motionmeasured in degrees as the ordinate for a restrained wire 5 for use byconnecting a lower mounting bar 4 to an upper mounting bar 3. From thisit appears that a very flat curve is obtained, so that even with arather large rotation of the restrained wire 5, a substantially constantmoment is obtained, and thereby a substantially constant force in alower mounting bar 4. The substantially flat portion 55 of the curve isthe area which is used in an orthodontic brace according to theinvention. The orthodontic brace will always be dimensioned in such away that the upper mounting bar 3 and each of the lower mounting bars 4always have such a stiffness that they will not be subjected to anydeformation of any importance by application of the spring forces whichare established by using the brace. The fastening means 9,27 is alsodimensioned in such a way that it does not bend during application ofthe forces to be transmitted.

FIGS. 20-23 show the use of the orthodontic brace 1 which is illustratedin FIG. 1 in connection with correction of the tooth segments 44,45,which are illustrated in FIG. 16. Initially the fastening means arepositioned at positions 46 as the arch wire 7 is positioned between thebranches of the U. Then the guiding system 2 is inserted with theindividual portions in a neutral position, that is to say without beingactivated. The rod 6 at the left side is fastened with the fasteningmeans 9. Next the brace 1 is activated (FIG. 21), and the rod at theright side is fastened with the fastening means 9 at the right side. Theorthodontic brace 1 is now in an active state secured between the twotooth segments 44,45. In the shown situation the tooth segment 45 has tobe displaced translationally against the tooth segment 44.

The actual mounting and the activating of the orthodontic brace israther uncomplicated as the joining force used will substantially beconstant even with a rather large deflection of the restrained wires 5.In FIG. 22 the tooth segment 45 is partially guided towards the toothsegment 44, and in FIG. 23 the two tooth segments 44,45 are broughtcompletely together, and the correction of the misaligned teeth isfinished. Thus, it will be possible to execute the steps oforthodontics, which are illustrated in FIGS. 21-23, by a singleactivating of the orthodontic brace 1.

If a very great distance appears between the tooth segments 44,45, anextra activating may be necessary. Alternatively, a very great distancebetween the tooth segments 44,45 will necessitate use of an orthodonticbrace of the type which is shown in FIGS. 5,8, or 9.

FIGS. 24 and 25 show the use of the orthodontic brace 1 which is shownin FIGS. 12 and 13. The orthodontic brace is mounted between the toothsegments 44 and 45. In this situation not only a translation should beinduced on the tooth segment 45 as it was illustrated in FIGS. 20-23.The tooth segment 45 has to provide a translation and a counterclockwise rotation. By using an orthodontic brace with a shorter wire 5'positioned at the side, which faces the secured segment, the lowerconnecting bar 4 at the right side, and accordingly the tooth segmentwill be displaced and rotated at the same time. After joining the toothsegments 44 and 45, the orthodontic brace will hold it in the shownposition in FIG. 25. Thus, the brace 1 has been able to carry out acombined translation and rotation by a single mounting and a singleactivating.

FIGS. 26 and 27 illustrate a correction of irregular teeth which isanalogous to the correction shown in FIGS. 24 and 25. In this use theshorter wire 5' is positioned nearest the tooth segment 45 which is tobe displaced and rotated. Consequently, this tooth segment is providedwith a counter clockwise rotation simultaneously with the translation inthe direction towards the tooth segment 44.

FIGS. 24-27 illustrate two specific situations of orthodonticcorrection. However, all possible relative movements between thesegments 44,45 may be obtained by changing the points of restraint, andthereby the lengths of the wires 5 used.

By using an orthodontic brace 1 according to the invention, a displacingof a tooth or a tooth segment 45 will occur on the basis of the concreteform of the guiding mechanism 2 consisting of the upper mounting bar 3,the lower mounting bars 4, and the wires 5 positioned between them. Asthe guiding mechanism 2 is effected by the spring force, which is formedby superelastic spring material 5,41,42, a substantially constant forceis obtained which may be kept at a rather low level that is optimizedregarding the biomechanical system.

Because of bending stability in the mounting bars 3,4 and in thefastening means 9,27, and possible attached rods and arch wires 6,7, themovement of the element of the guiding mechanism 2 will give rise to aself-adjusting contribution of moment which is exerted on a tooth or atooth segment via the adhered brackets 8. If the spring forces areexerted to a bracket 8 at a distance from the centre of resistance sothat a moment is formed, the torsion stable engaging of the arch wirewith a bracket 8 will give rise to a compensating moment 53. Thus, theuse of an orthodontic brace 1 according to the invention will be verysimple, as a user does not need to carry out individual adjustments inorder to adjust an established spring force and an established moment toa given situation of orthodontic correction.

When the user has established whether there is a need for a puretranslation or a translation combined with a rotation, an orthodonticbrace is chosen which is mounted and activated, after which a correctforce and a possible contribution of moment is exerted automaticallybecause of the form of the guiding mechanism 2. The orthodontic brace 1is very easy to use as it merely requires fastening of a nut 12 or ascrew 28. The actual fastening may take place by means of a per se knowntorque wrench to ensure a correct fastening.

We claim:
 1. An orthodontic brace for moving teeth comprisingforce-transmitting means connected with the teeth to be moved fortransmitting an actuation force to the teeth; a guiding mechanism with abending stable, upper mounting bar, two bending stable, lower mountingbars which extend substantially parallel to the upper mounting bar, anda spring means of a superelastic material; and a fastening means forconnecting the guiding mechanism with the force-transmitting means, saidspring means resiliently actuating said two lower mounting bars andcausing desired movement of said teeth.
 2. An orthodontic braceaccording to claim 1, wherein said spring means comprise two pairs ofwires made of superelastic material, each pair of wires comprising twoparallel wires which connect said bending stable upper mounting bar witha respective bending stable lower mounting bar.
 3. An orthodontic braceaccording to claim 2, wherein the superelastic wires are restrained inthe mounting bars by moulding into the upper mounting bars and byclamping into a tube, which together with a bar, which is used forfastening the orthodontic brace, constitutes each of the lower mountingbars, said tubes being fastened to the bar by soldering or welding. 4.An orthodontic brace according to claim 1, wherein said guidingmechanism includes wires connected with the mounting bars by a hugejoint, and wherein said spring means comprises a U-shaped spring or acoil spring mounted between the two lower mounting bars.
 5. Anorthodontic brace according to claim 2, wherein at least one of thewires has a length shorter than the length of the other wires as theyare mounted in a projecting portion of a mounting bar.
 6. An orthodonticbrace according to claim 1, wherein the upper mounting bar is made oftwo telescopic portions, and the lower mounting bars are connected witheach of said telescopic portions.
 7. An orthodontic brace according toclaim 1, wherein the fastening means are constituted of a U-shapedclamping device which is intended for accommodating a rod-shaped portionof the lower mounting bar and an arch wire, wherein the U-shapedclamping device is formed by a U-shaped strip in which the fourrectangular corner portions are removed in such a way that centralportion of the outermost portions of the U-shaped strip may accommodatea nut, which is secured in a position for rotation as outermost centralportions of a branch of the U-shaped strip is bent outwardly forformation of flaps which prevent removal of the nut as a displaceablepawl is provided between the two branches of the U-shaped strip, saidpawl being in engagement with the nut through a thread.
 8. Anorthodontic brace according to claim 7, wherein a distance between thebranches of the U-shaped strip substantially correspond to the crossdimension of the tubular rod of the mounting bar and the cross dimensionof the arch wire, and the width of the U-shaped strip is between 2 and10 times said distance between the branches.
 9. An orthodontic braceaccording to claim 7, wherein the flaps formed on the outermost centralportions of the branches of the U-shaped strip have such a dimensionthat the central end portion of the U-shaped strip in a compressed statemay pass through the nut.
 10. An orthodontic brace according to claim 7,wherein both a bottom of the U-shaped strip and the end of thedisplaceable pawl facing an interior of the U-shaped strip are made oftwo substantially plane surfaces which form a V-shape having a mutualangle of between 30° and 120°.